[V2 30/36] [SFrame-V3] ld: add --discard-sframe command line option
Indu Bhagat
indu.bhagat@oracle.com
Wed Jan 7 08:42:21 GMT 2026
Add a new command line option --discard-sframe to the linker.
This option allows users to prevent the linker from generating an output
.sframe section.
The rationale for this option is: Consider the case when say, the distro
is shipped with SFrame sections in the installed binaries/libraries. A
user application using these installed libraries, but not enabling
.sframe for itself just yet, will see an output .sframe corresponding to
the pulled in libraries. This is "partial" .sframe information for the
application. Adding such an option to the linker, gives user a way to
turn off the .sframe section completely without relying on a linker
script.
Previously, the existing --no-ld-generated-unwind-info option
controlled whether (not just .eh_frame for PLT entries, but also) SFrame
for PLT entries. The new command line option,
--discard-sframe now decouples SFrame from other unwind
formats (like .eh_frame), allowing for more control over the output
binary's SFrame data.
The option is added for architectures that currently support SFrame:
AArch64, s390x, and x86_64.
In a subsequent commit, we will tie this option with discard of all
input .sframe sections.
TBD:
- (Input from reviewers appreciated) For aarch64, is adding to both
aarch64elf.sh and aarch64linux.sh necessary? The desired outcome is
to allow the new command line for aarch64 elf, amd64 elf, s390x elf
only. Confirm.
bfd/
* elf64-s390.c (elf_s390_create_dynamic_sections): Use
discard_sframe to guard .sframe section creation.
* elfxx-x86.c (_bfd_x86_elf_link_setup_gnu_properties): Likewise.
include/
* bfdlink.h (struct bfd_link_info): Add discard_sframe bitfield.
ld/
* ldlex.h (enum option_values): Add OPTION_NO_LD_SFRAME_INFO.
* lexsup.c (elf_sframe_list_options): New function.
(ld_list_options): Add sframe_info argument. Update callers.
* emulparams/sframe-info.sh: New file.
* emulparams/aarch64elf.sh: Source sframe-info.sh.
* emulparams/aarch64linux.sh: Likewise.
* emulparams/elf64_s390.sh: Likewise.
* emulparams/elf_x86_64.sh: Likewise.
* Makefile.am: Update to handle sframe-info.sh and new list options.
* configure.ac: Handle SFRAME_INFO target variable.
* Makefile.in: Regenerate.
* configure: Regenerate.
---
[Changes in V1]
- Use dash in new files instead of underscore [Jan].
- Rename to --discard-sframe-sections [Jan, Augustine].
- Added documentation in ld.texi [Jan].
[End of Changes in V1]
[Changes in V2]
- Rename --discard-sframe-sections to --discard-sframe [Jan, Indu].
- Commit log adjustments.
[End of changes in V2]
---
bfd/elf64-s390.c | 2 +-
bfd/elfxx-x86.c | 2 +-
include/bfdlink.h | 4 ++++
ld/Makefile.am | 3 ++-
ld/Makefile.in | 4 +++-
ld/configure | 11 +++++++++--
ld/configure.ac | 6 ++++++
ld/emulparams/aarch64elf.sh | 1 +
ld/emulparams/aarch64linux.sh | 1 +
ld/emulparams/elf64_s390.sh | 1 +
ld/emulparams/elf_x86_64.sh | 1 +
ld/emulparams/sframe-info.sh | 15 +++++++++++++++
ld/ld.texi | 10 +++++++---
ld/ldlex.h | 2 ++
ld/lexsup.c | 15 +++++++++++++--
15 files changed, 67 insertions(+), 11 deletions(-)
create mode 100644 ld/emulparams/sframe-info.sh
diff --git a/bfd/elf64-s390.c b/bfd/elf64-s390.c
index 012457827e0..8ad10ce6bd1 100644
--- a/bfd/elf64-s390.c
+++ b/bfd/elf64-s390.c
@@ -4309,7 +4309,7 @@ elf_s390_create_dynamic_sections (bfd *dynobj,
}
/* Create .sframe section for .plt section. */
- if (!info->no_ld_generated_unwind_info)
+ if (!info->discard_sframe)
{
flagword flags = (SEC_ALLOC | SEC_LOAD | SEC_READONLY
| SEC_HAS_CONTENTS | SEC_IN_MEMORY
diff --git a/bfd/elfxx-x86.c b/bfd/elfxx-x86.c
index f2ace269f3e..0c61b61830a 100644
--- a/bfd/elfxx-x86.c
+++ b/bfd/elfxx-x86.c
@@ -4837,7 +4837,7 @@ _bfd_x86_elf_link_setup_gnu_properties
}
/* .sframe sections are emitted for AMD64 ABI only. */
- if (ABI_64_P (info->output_bfd) && !info->no_ld_generated_unwind_info)
+ if (ABI_64_P (info->output_bfd) && !info->discard_sframe)
{
flagword flags = (SEC_ALLOC | SEC_LOAD | SEC_READONLY
| SEC_HAS_CONTENTS | SEC_IN_MEMORY
diff --git a/include/bfdlink.h b/include/bfdlink.h
index d715fcbd6fb..eac72b8c388 100644
--- a/include/bfdlink.h
+++ b/include/bfdlink.h
@@ -475,6 +475,10 @@ struct bfd_link_info
linker created sections, TRUE if it should be omitted. */
unsigned int no_ld_generated_unwind_info: 1;
+ /* TRUE if no .sframe stack trace info should be generated for the output.
+ This includes linker generated SFrame info as well. */
+ unsigned int discard_sframe: 1;
+
/* TRUE if BFD should generate a "task linked" object file,
similar to relocatable but also with globals converted to
statics. */
diff --git a/ld/Makefile.am b/ld/Makefile.am
index 3f2a9ae9832..c219662d2e3 100644
--- a/ld/Makefile.am
+++ b/ld/Makefile.am
@@ -42,7 +42,8 @@ ZLIBINC = @zlibinc@
ELF_CFLAGS=-DELF_LIST_OPTIONS=@elf_list_options@ \
-DELF_SHLIB_LIST_OPTIONS=@elf_shlib_list_options@ \
- -DELF_PLT_UNWIND_LIST_OPTIONS=@elf_plt_unwind_list_options@
+ -DELF_PLT_UNWIND_LIST_OPTIONS=@elf_plt_unwind_list_options@ \
+ -DELF_SFRAME_LIST_OPTIONS=@elf_sframe_list_options@
WARN_CFLAGS = @WARN_CFLAGS@
NO_WERROR = @NO_WERROR@
AM_CFLAGS = $(WARN_CFLAGS) $(ELF_CFLAGS) $(JANSSON_CFLAGS) $(ZSTD_CFLAGS)
diff --git a/ld/Makefile.in b/ld/Makefile.in
index 0af36e9e310..f1ba6af5269 100644
--- a/ld/Makefile.in
+++ b/ld/Makefile.in
@@ -520,6 +520,7 @@ docdir = @docdir@
dvidir = @dvidir@
elf_list_options = @elf_list_options@
elf_plt_unwind_list_options = @elf_plt_unwind_list_options@
+elf_sframe_list_options = @elf_sframe_list_options@
elf_shlib_list_options = @elf_shlib_list_options@
enable_initfini_array = @enable_initfini_array@
enable_libctf = @enable_libctf@
@@ -579,7 +580,8 @@ ZLIB = @zlibdir@ -lz
ZLIBINC = @zlibinc@
ELF_CFLAGS = -DELF_LIST_OPTIONS=@elf_list_options@ \
-DELF_SHLIB_LIST_OPTIONS=@elf_shlib_list_options@ \
- -DELF_PLT_UNWIND_LIST_OPTIONS=@elf_plt_unwind_list_options@
+ -DELF_PLT_UNWIND_LIST_OPTIONS=@elf_plt_unwind_list_options@ \
+ -DELF_SFRAME_LIST_OPTIONS=@elf_sframe_list_options@
AM_CFLAGS = $(WARN_CFLAGS) $(ELF_CFLAGS) $(JANSSON_CFLAGS) $(ZSTD_CFLAGS)
diff --git a/ld/configure b/ld/configure
index f557d53b1c3..99d0ace48ea 100755
--- a/ld/configure
+++ b/ld/configure
@@ -644,6 +644,7 @@ EMUL_EXTRA_OFILES
EMULATION_OFILES
TDIRS
EMUL
+elf_sframe_list_options
elf_plt_unwind_list_options
elf_shlib_list_options
elf_list_options
@@ -11893,7 +11894,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 11896 "configure"
+#line 11897 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@@ -11999,7 +12000,7 @@ else
lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
lt_status=$lt_dlunknown
cat > conftest.$ac_ext <<_LT_EOF
-#line 12002 "configure"
+#line 12003 "configure"
#include "confdefs.h"
#if HAVE_DLFCN_H
@@ -19211,6 +19212,7 @@ TDIRS=
elf_list_options=false
elf_shlib_list_options=false
elf_plt_unwind_list_options=false
+elf_sframe_list_options=false
for targ_alias in `echo $target_alias $enable_targets | sed 's/,/ /g'`
do
if test "$targ_alias" = "all"; then
@@ -19218,6 +19220,7 @@ do
elf_list_options=true
elf_shlib_list_options=true
elf_plt_unwind_list_options=true
+ elf_sframe_list_options=true
else
# Canonicalize the secondary target names.
result=`$ac_config_sub $targ_alias 2>/dev/null`
@@ -19273,6 +19276,9 @@ tdir_$i=$result"
if test x${PLT_UNWIND} = xyes; then
elf_plt_unwind_list_options=true
fi
+ if test x${SFRAME_INFO} = xyes; then
+ elf_sframe_list_options=true
+ fi
fi
;;
esac
@@ -19481,6 +19487,7 @@ _ACEOF
+
if test x${all_targets} = xtrue; then
if test x${have_64_bit_bfd} = xyes; then
EMULATION_OFILES='$(ALL_EMULATIONS) $(ALL_64_EMULATIONS)'
diff --git a/ld/configure.ac b/ld/configure.ac
index 40ca00907e0..e4c1507ff77 100644
--- a/ld/configure.ac
+++ b/ld/configure.ac
@@ -506,6 +506,7 @@ TDIRS=
elf_list_options=false
elf_shlib_list_options=false
elf_plt_unwind_list_options=false
+elf_sframe_list_options=false
for targ_alias in `echo $target_alias $enable_targets | sed 's/,/ /g'`
do
if test "$targ_alias" = "all"; then
@@ -513,6 +514,7 @@ do
elf_list_options=true
elf_shlib_list_options=true
elf_plt_unwind_list_options=true
+ elf_sframe_list_options=true
else
# Canonicalize the secondary target names.
result=`$ac_config_sub $targ_alias 2>/dev/null`
@@ -568,6 +570,9 @@ tdir_$i=$result"
if test x${PLT_UNWIND} = xyes; then
elf_plt_unwind_list_options=true
fi
+ if test x${SFRAME_INFO} = xyes; then
+ elf_sframe_list_options=true
+ fi
fi
;;
esac
@@ -730,6 +735,7 @@ AC_DEFINE_UNQUOTED([DEFAULT_EMIT_GNU_HASH],
AC_SUBST(elf_list_options)
AC_SUBST(elf_shlib_list_options)
AC_SUBST(elf_plt_unwind_list_options)
+AC_SUBST(elf_sframe_list_options)
AC_SUBST(EMUL)
AC_SUBST(TDIRS)
diff --git a/ld/emulparams/aarch64elf.sh b/ld/emulparams/aarch64elf.sh
index aa051c76a7a..c788c692ba0 100644
--- a/ld/emulparams/aarch64elf.sh
+++ b/ld/emulparams/aarch64elf.sh
@@ -1,3 +1,4 @@
+source_sh ${srcdir}/emulparams/sframe-info.sh
source_sh ${srcdir}/emulparams/dt-relr.sh
ARCH=aarch64
diff --git a/ld/emulparams/aarch64linux.sh b/ld/emulparams/aarch64linux.sh
index 6fe82a70659..d6369fa9e94 100644
--- a/ld/emulparams/aarch64linux.sh
+++ b/ld/emulparams/aarch64linux.sh
@@ -1,3 +1,4 @@
+source_sh ${srcdir}/emulparams/sframe-info.sh
source_sh ${srcdir}/emulparams/dt-relr.sh
ARCH=aarch64
diff --git a/ld/emulparams/elf64_s390.sh b/ld/emulparams/elf64_s390.sh
index b58314800d1..750e83b714f 100644
--- a/ld/emulparams/elf64_s390.sh
+++ b/ld/emulparams/elf64_s390.sh
@@ -1,4 +1,5 @@
source_sh ${srcdir}/emulparams/plt_unwind.sh
+source_sh ${srcdir}/emulparams/sframe-info.sh
SCRIPT_NAME=elf
ELFSIZE=64
OUTPUT_FORMAT="elf64-s390"
diff --git a/ld/emulparams/elf_x86_64.sh b/ld/emulparams/elf_x86_64.sh
index fb4fcd6ae17..747114bc4b4 100644
--- a/ld/emulparams/elf_x86_64.sh
+++ b/ld/emulparams/elf_x86_64.sh
@@ -1,4 +1,5 @@
source_sh ${srcdir}/emulparams/plt_unwind.sh
+source_sh ${srcdir}/emulparams/sframe-info.sh
source_sh ${srcdir}/emulparams/extern_protected_data.sh
source_sh ${srcdir}/emulparams/dynamic_undefined_weak.sh
source_sh ${srcdir}/emulparams/reloc_overflow.sh
diff --git a/ld/emulparams/sframe-info.sh b/ld/emulparams/sframe-info.sh
new file mode 100644
index 00000000000..b7cc10bd981
--- /dev/null
+++ b/ld/emulparams/sframe-info.sh
@@ -0,0 +1,15 @@
+SFRAME_INFO=yes
+
+PARSE_AND_LIST_LONGOPTS_SFRAME='
+ {"discard-sframe", no_argument, NULL,
+ OPTION_DISCARD_SFRAME},
+'
+
+PARSE_AND_LIST_ARGS_CASES_SFRAME='
+ case OPTION_DISCARD_SFRAME:
+ link_info.discard_sframe = true;
+ break;
+'
+
+PARSE_AND_LIST_LONGOPTS="$PARSE_AND_LIST_LONGOPTS $PARSE_AND_LIST_LONGOPTS_SFRAME"
+PARSE_AND_LIST_ARGS_CASES="$PARSE_AND_LIST_ARGS_CASES $PARSE_AND_LIST_ARGS_CASES_SFRAME"
diff --git a/ld/ld.texi b/ld/ld.texi
index 85272e4b6f6..77be53cb317 100644
--- a/ld/ld.texi
+++ b/ld/ld.texi
@@ -3247,9 +3247,13 @@ section and ELF @code{PT_GNU_EH_FRAME} segment header.
@item --no-ld-generated-unwind-info
Request creation of @code{.eh_frame} unwind info for linker
generated code sections like PLT. This option is on by default
-if linker generated unwind info is supported. This option also
-controls the generation of @code{.sframe} stack trace info for linker
-generated code sections like PLT.
+if linker generated unwind info is supported.
+
+@kindex --discard-sframe
+@item --discard-sframe
+Discard @code{.sframe} stack trace info from the output. This option also
+prohibits the creation of SFrame stack trace data for linker generated code
+sections like PLT. This option is off by default.
@kindex --enable-new-dtags
@kindex --disable-new-dtags
diff --git a/ld/ldlex.h b/ld/ldlex.h
index 1efbe58002b..85e06b6fcc4 100644
--- a/ld/ldlex.h
+++ b/ld/ldlex.h
@@ -215,6 +215,8 @@ enum option_values
/* Used by emulparams/plt_unwind.sh. */
OPTION_LD_GENERATED_UNWIND_INFO,
OPTION_NO_LD_GENERATED_UNWIND_INFO,
+ /* Used by emulparams/sframe-info.sh. */
+ OPTION_DISCARD_SFRAME,
/* Used by emultempl/aarch64elf.em. */
OPTION_FIX_ERRATUM_835769,
OPTION_FIX_ERRATUM_843419,
diff --git a/ld/lexsup.c b/ld/lexsup.c
index 843b809bacb..158abb6dd8f 100644
--- a/ld/lexsup.c
+++ b/ld/lexsup.c
@@ -2364,13 +2364,23 @@ elf_plt_unwind_list_options (FILE *file)
}
static void
-ld_list_options (FILE *file, bool elf, bool shlib, bool plt_unwind)
+elf_sframe_list_options (FILE *file)
+{
+ fprintf (file, _("\
+ --discard-sframe Don't generate SFrame stack trace info in output\n"));
+}
+
+static void
+ld_list_options (FILE *file, bool elf, bool shlib, bool plt_unwind,
+ bool sframe_info)
{
if (!elf)
return;
printf (_("ELF emulations:\n"));
if (plt_unwind)
elf_plt_unwind_list_options (file);
+ if (sframe_info)
+ elf_sframe_list_options (file);
elf_static_list_options (file);
if (shlib)
elf_shlib_list_options (file);
@@ -2495,7 +2505,8 @@ help (void)
/* xgettext:c-format */
printf (_("%s: emulation specific options:\n"), program_name);
ld_list_options (stdout, ELF_LIST_OPTIONS, ELF_SHLIB_LIST_OPTIONS,
- ELF_PLT_UNWIND_LIST_OPTIONS);
+ ELF_PLT_UNWIND_LIST_OPTIONS,
+ ELF_SFRAME_LIST_OPTIONS);
ldemul_list_emulation_options (stdout);
printf ("\n");
--
2.43.0
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